With another two publications on halide perovskites (HaPs) last week, Sampson really seems to be on a winning streak.
One of the bottlenecks of HaPs is their stability. Formamidinium lead iodide (FAPbI3), for example, tends to change its phase from a desirable light absorbing black phase into a yellow phase with a band gap that is too wide for successful employment in single junction solar cells. In an intersting approach, Sampson the blade-coating method to deposit a smooth film of so-called two-timdensional HaP, which he successively converted into 3D FAPbI3 with an increased stability. Read the full open access publication here.
In his second report, Sampson sought to improve the stability of the notoriously unstable tin compound FASnI3 by introducing strontium into the structure. Tin-based perovskites suffer from the easiy oxidation of tin from its desired +2 state into an undesired +4 state. Strontium, on the other hand only has one oxidation state (2+) and exhibits almost the same ionic radius as Sn(2+). Mixining these elements, however, does not lead to homogenous films, but rather a perovskite with tin-rich core surrounded by a strontium-rich surface layer. For more information see here.